Slab foundations can be found under many homes. Typically, this type of structural base sits over soil or gravel and helps to distribute the weight of the building above it. The thickness of slab foundations vary depending on the type of structure they hold. If the soil underneath the slab is not prepared properly, cracks can appear in the slab. The term “cracked slab” can be used to describe a variety of slab foundation problems.
Slab crack repair varies depending on the type of crack, the cause of the crack and its severity. A small hairline crack running through a floor tile may not always be cause for alarm -- in areas where drought conditions have been suffered, tile with a hairline crack may be the result of soil settlement. A slab crack that continues up into the home’s wall is a cause for concern and should be examined by a qualified repair specialist.
A cracked slab also may be the result of shrinkage in the concrete or building materials, foundation settling or slab foundation movement caused by frost heaves and/or expansive soil. In general, shrinkage cracks do not compromise the building’s structural integrity, but they can lead to water leaks and crawl space moisture. Cracked slabs from soil settlement also can lead to unwanted moisture.
Slab foundation cracks caused by expansive soils (such as clay soils) or frost heaves can create several problems. Expansive soil also may be known as shrink-swell soil. An expansive soil, such as a soil with a high clay concentration, does not drain as well as other soils. Instead, when the clay soils get wet, they absorb the water molecules and expand, or swell. When the clay dries out it contracts or “shrinks.” This swelling or expansion when wet can cause the soil to heave upward towards the slab foundation and over time can cause cracking. The shrinkage of the soil as it dries can contribute to the foundation settling, creating cracks or other issues.
Cracked slabs due to expansive soils or other conditions need to be inspected by a foundation repair specialist. When left unchecked, foundation problems can cause serious structural damage to the home. Contact a repair specialist to prevent further damage from occurring.